CN105682805A - Pre-comminuting device for a ball mill or agitator ball mill, and ball mill with pre-comminuting device - Google Patents

Abstract

The invention relates to a pre-comminuting device (7) for a ball mill or agitator ball mill (1), wherein the pre-comminuting device (7) is arranged between a milling material inlet (4) of the ball mill or agitator ball mill (1) and a milling space (2R) and comprises a first stationary comminuting means (20) and a second rotationally movable comminuting means (30) between which a comminuting gap (S) is formed. The first stationary comminuting means (20) is a comminuting ring (21) arranged in the milling container (2). According to the invention, the first stationary comminuting means (20) has an inner toothing (26). The second comminuting means (30) comprises a first subregion (34) and a second subregion (35). The second subregion (35) has guiding structures (37) for the milling material, via which the milling material can be guided in the direction of the first subregion (34). The first subregion (34) of the second comminuting means (30) comprises a first outer toothing (36). The first comminuting means (20) and the second comminuting means (30) are arranged such that the outer toothing (36) of the first subregion (34) of the second comminuting means (30) substantially engages in the inner toothing (26) of the first comminuting means (20) to form the comminuting gap (S). The invention further relates to a ball mill (1) with pre-comminuting device (7).

Description

Pre-grinding device for ball mill or agitator ball mill and ball mill with pre-grinding device

technical field

The invention relates to a pre-grinding device suitable for a ball mill or an agitator ball mill according to the features in the preamble of claim 1 and to a ball mill with a pre-grinding device according to the features in the preamble of claim 11 .

Background technique

The present invention relates to a pre-grinding device suitable for a ball mill or an agitator ball mill and a ball mill with a pre-grinding device. Ball mill is a device suitable for coarse, fine and extremely fine grinding or homogenization of grinding materials. It comprises a grinding chamber which is caused to rotate, wherein the grinding material is ground by grinding bodies in the grinding chamber. Ball mills generally include a generally cylindrical grinding vessel mounted for horizontal rotation. The ball mill is filled through a central opening at one of the end walls, the so-called grinding stock inlet. The output depends on the design and takes place, for example, via grooves in the grinding chamber wall at the end of the ball mill, wherein the grinding bodies are blocked by the separating device.

A special form of ball mill is the agitator ball mill. Agitator ball mills comprise a vertically or horizontally arranged, generally approximately cylindrical grinding vessel, which is 70% to 90% filled with grinding bodies. In the case of agitator ball mills, the grinding chamber is usually mounted stationary, non-rotating. A stirrer with suitable stirring elements provides high-intensity movement of the grinding bodies. The grinding material suspension is continuously pumped through the grinding chamber. Suspended solids are ground or dispersed by impact or shear forces between the grinding bodies. Separation of ground stock and ground bodies is carried out by means of a suitable separation device at the outlet from the mill.

Document DD217434B1 describes a vertically arranged agitating ball mill comprising, in the upper inlet region, a pre-grinding device connected to the agitating shaft. The pre-grinding device comprises a grinding cone arranged rotatably fixed to the stirring shaft and a grinding ring fixed to the grinding container. The ground material is introduced into the grinding gap between the grinding cone and the grinding ring and is thus pre-ground before it falls into the grinding container, where it is further ground by the stirring shaft and grinding bodies processing.

The document DE102008058585A1 discloses a stirring ball mill with a horizontally arranged grinding chamber and a stirring shaft, wherein the pre-grinding device is arranged between the grinding material inlet and the grinding chamber, and the pre-grinding device comprises a gap to the grinding chamber Protect. This thus prevents the grinding bodies from being able to flow back into the pre-grinding device.

EP1980323B1 describes a cutting system with a cutting rotor comprising rotor bars at an outwardly facing surface, about which a rotor cutting plate with a cutting edge is fixed. A stator ring having an annular base and stator bars is disposed around the cutting rotor. The stator bars each include inwardly facing stator grooves with stator cut plates. The stator cutting plates are respectively arranged and fixed such that they are respectively positioned opposite to the rotor cutting plates.

The problem to be solved by the present invention is to improve the pre-grinding of the solid constituents of the ground mass, in particular to provide a pre-grinding device in which the clogging problems of coarse particles and/or impurities are reduced or minimized.

The above-mentioned problems are solved by a pre-grinding device for a ball mill or an agitator ball mill comprising the features of claim 1 and by a ball mill with a pre-grinding device including the features of claim 11 . Further advantageous embodiments are described by the dependent claims.

Contents of the invention

The present invention relates to a pre-grinding device suitable for ball mills or agitator ball mills. The pre-grinding device is arranged in the grinding container between the grinding stock inlet and the grinding chamber of the ball mill or agitator ball mill, and is used in particular to carry out a pre-grinding of the ground stock, so that the ground stock which enters the grinding chamber now preferably only comprises A component with a predetermined maximum size. The pre-grater device comprises a first grater device which is stationary and a second grater device which is rotatably movable, a grating gap being formed between the first grater device and the second grater device. The stationary first grinding device is in particular a grinding ring arranged in the grinding chamber.

According to the invention, the stationary first grater comprises an internal tooth system. The second grater comprises a first subregion and a second subregion. The grating gap is formed in particular between the first subregion of the stationary first and second grating means. The second sub-region of the second grinding device comprises guide structures adapted to grind material. The guide structure serves in particular to feed the grinding material entering via the grinding material inlet in the direction of the first sub-region of the second grinding device and thus in the pre-grinding device formed between the grinding ring and the first sub-region. Feed in the direction of the grinding gap between the zones.

The first subregion of the second grater comprises a first external toothing system. The first grater and the second grater are arranged in such a way that the external tooth system of the first subregion of the second grater engages mostly to the internal tooth system of the first grater, in particular the grinding ring, by This forms the grinding gap. The grinding gap forms the minimum distance between the internal tooth system and the external tooth system. The internal toothing system and the external toothing system can, for example, be formed largely in a form-fitting manner with one another. However, the teeth are separated from each other by a minimum distance of the grater gap, ie the teeth of the two grater appliances do not touch each other.

According to a preferred embodiment, the guide structure of the second subregion of the second grater is formed by the sparse external toothing system of this subregion. In particular, the second subregion comprises a second external toothing system with a second external toothing having a second tooth height and a second tooth width. The second tooth height and the second tooth width are greater than the first tooth height and the first tooth width of the aforementioned first outer teeth in the first subregion of the second grater.

A sparse external toothing system has in particular a tooth width of an individual tooth which, when viewed in the direction of the adjacent first subregion, increases from the free end of the second subregion. Alternatively and/or additionally, the tooth height of the second external toothing can also decrease in the direction of the adjacent first subregion. The description of the tooth shape relates in particular to the outer surface of said second outer toothing.

According to one embodiment of the invention, the side surfaces delimiting the outer surface of the second external toothing have a curved course. In particular, one of the two flanks has a more pronounced curvature, as a result of which a widening of the outer surface of the second outer toothing is formed in the direction of the adjacent first subregion.

According to one embodiment, the first external tooth system of the first subregion of the second grater extends on the outer surface of the second external tooth system of the second subregion, i.e. the second subregion already constitutes a so-called double tooth system , wherein the outer surface of the sparse external tooth system has a superimposed fine tooth system. The fine tooth system essentially corresponds to the first external tooth system of the first subregion of the second grater.

According to a particularly preferred embodiment, the second subregion of the second rotatably displaceable grater is designed as a frustoconical region with a frustoconical base and a frustoconical top. The first subregion can be formed as an approximately cylindrical region with a cylindrical base. Alternatively, the first subregion can also be formed as a frustoconical region. The base of the frustum of the second subregion is approximately the same as the base of the cylinder of the first subregion. A substantially cylindrical region having a cylindrical base is positioned adjacent to the frusto-conical base of the frusto-conical region. In this embodiment, a first external toothing system with a first external toothing having a first tooth height and a first tooth width is assigned to the substantially cylindrical region. The first external teeth are designed to correspond to the internal teeth of the internal tooth system of the first grater, in particular to the internal teeth of the internal tooth system of the grater ring. The first grater and the second grater are arranged in such a way that the external tooth system of the cylindrical area largely engages the internal tooth system of the first grater, thereby forming a grating gap, wherein the grating gap forms the internal tooth system Minimum distance to external toothing system.

The frusto-conical region of the second grater comprises a second external toothing system with second external teeth in the region of the outer side surface between the frusto-conical top surface and the frusto-conical bottom surface. The second external teeth have a second tooth height and a second tooth width which are greater than the first tooth height and the first tooth width of the first external teeth in the cylindrical region of the second grater. Furthermore, provision can be made for the tooth width of the second external toothing to increase from the top of the truncated cone in the direction of the cylindrical region and/or for the tooth height of the second external toothing to decrease in the direction of the cylindrical region. In particular, the sides or edges respectively delimiting the outer surfaces of the outer teeth have a curvature. In particular, one of the flanks is more pronouncedly curved, with the result that a widening of the second external toothing in the direction of the cylindrical region occurs. The first external tooth system of the cylindrical region of the second grater preferably continues on the second external tooth system of the frusto-conical region of the second grater.

The invention relates to a device for pre-grinding coarse-grained ingredients, in particular nuts, in the inlet region of a ball mill or agitator ball mill, in particular in the region between the grinding material inlet and the grinding chamber. Ball mills or agitator ball mills are used in particular for grinding wet ground materials, but can also be used for dry grinding operations. The pre-grater device is in particular composed of two parts and comprises a stationary grinding ring and a movable, in particular rotatable, grater. The grinding ring comprises an internal tooth system in the region of the inner side surface. The grater comprises a first region with a first tooth having a first material thickness and/or a first material height and a second region having a first tooth having a first material thickness and/or a first material height and a second tooth having a The first material thickness and/or first material height and the second tooth have a second material thickness and/or second material height of the second tooth. The first material thickness and/or the first material height are preferably smaller than the second material thickness and/or the second material height. In particular, the first material thickness and/or first material height of the teeth of the grater corresponds to the material thickness and/or material height of the inner teeth of the grater ring. The second teeth of the grater are thicker in the region of the entry of the pre-grater than the thickness of the first teeth of the grater in the region of the grating or comminution ring.

The sparse second teeth in the second region of the grater also have a tapering tooth shape. In particular, the tooth shape tapers in the direction of the free end region of the truncated-conical grater facing away from the grater ring or in the direction of the top surface of the grater designed as a truncated cone.

As a result of the larger second teeth of the grinder, coarse particles can be better picked up and pre-grinded. The entire pre-grinding device is constructed and arranged between the grinding stock inlet and the grinding chamber in such a way that as little as possible no dead space is formed in order to avoid coarse particles and/or impurities being stuck. The present inventors have found that ball mills or agitator ball mills are particularly suitable for the production of chocolate mass, chocolate fillings and other food products. However, the invention is also applicable to other products to be ground, and can also be used for suspensions of ground material, or, given suitable dimensions, also for the pre-grinding of ground material in mining or the like.

The novelty of the present invention thus consists in the combination of a fine tooth system and a sparse tooth system, in particular a tapered tooth shape with a sparse tooth system, which results in a better performance in the case of coarse-grained product ingredients. ingress behavior, especially when the milled material includes product components of different sizes. As a result of the sparse tooth system, a greater tooth depth is formed on the inlet side. A better pumping effect and/or turbulent flow is thus achieved by the pre-grinding device according to the invention, which prevents the grinding stock or product from sticking in the inlet area.

The finished first grinding device, in particular a grinding ring provided with an internal tooth system, is arranged and fixed in the grinding container of the ball mill or agitator ball mill. The grinding ring is arranged in such a way that it divides the interior space of the ball mill or agitator ball mill into a grinding chamber and a preparation chamber. The second grater is arranged and fixed to the axis of rotation along the longitudinal axis of the grinding container, whereby the first subregion of the second grater with the first external teeth is arranged such that: the first external teeth mostly engage To the internal tooth system of the grinding ring, thereby forming a grinding gap, which forms a minimum distance. The second subregion of the second grinding device is then arranged in the preparation chamber between the grinding material inlet of the ball mill or agitator ball mill and the first grinding device or grinding chamber.

The first stationary grinder generally has an outer diameter which approximately corresponds to the inner diameter of the grinding container and is arranged and fixed in the grinding container. According to one embodiment of the present invention, the second grinding device is arranged and fixed to the rotatable stirring shaft of the stirring ball mill. When the pre-grinding device is used in a ball mill, its own drive is provided for the second grinder.

By means of the device according to the invention, ground material suitable for large mills, in particular wet mills, can advantageously be pre-ground before it is further processed in the grinding chamber by means of auxiliary grinding means. As a result of the sparse tooth system of the rotating grinder, the introduction of the grinding stock into the grinding chamber is also improved and residues of the grinding stock in the preparation chamber between the grinding stock inlet and the grinding chamber are at least largely prevented.

The pre-grinding device according to the invention can be integrated directly into the mill during assembly of the mill. However, it is also possible to subsequently retrofit the mill by means of the pre-shredding device according to the invention, the existing pre-shredding device having to be dismantled beforehand if appropriate.

Description of drawings

Examples of embodiments of the invention and their advantages are explained in more detail below with the aid of the drawings. The dimensional ratios of various elements relative to each other in the drawings do not always correspond to actual dimensional ratios because some shapes are shown simplified and other shapes are shown exaggerated relative to other elements for better explanation.

FIG. 1 shows a schematic view of an agitated ball mill with a vertically arranged grinding vessel and an agitator according to the prior art.

FIG. 2 shows a schematic view of an agitated ball mill with a horizontally arranged grinding vessel and agitator according to the prior art.

Figure 3 shows several views of the first grater appliance of the pre-grater device according to the invention.

Figure 4 shows several views of the second grater of the pre-grater device according to the invention.

Figure 5 shows a detail of the tooth system between the first grater and the second grater.

Figure 6 shows a sectional view through a pregrater according to the invention.

detailed description

The same reference numerals are used for identical or identically acting elements of the invention. Furthermore, for greater clarity, reference signs are only present in the respective figures that are required for the corresponding figure in the description. The presented embodiments represent only examples in order to show how the device according to the invention or the method according to the invention may be structured and do not represent a decisive limitation.

FIG. 1 shows a schematic diagram of an agitator ball mill 1 a according to the prior art with a vertically arranged grinding vessel 2 and an agitator 3 . The agitator ball mill 1 a comprises an upper grinding stock inlet 4 and a lower grinding stock outlet 5 to which a separating device 6 is assigned. The separating device 6 blocks grinding bodies (not shown) in the grinding container 2 . The agitator ball mill 1 a also includes a pre-grinding device 7 connected to the agitator shaft 3 * of the agitator 3 . The pre-grinding device comprises a crushing cone 8 arranged to be rotatably fixed to the stirring shaft 3 * and a crushing ring 9 fixed to the grinding container 2 . The ground material is introduced into the grinding gap S between the grinding cone 8 and the grinding ring 9 and is thus pre-ground before it falls into the grinding container 2 where it passes through the agitator 3 and the grinding body is further processed. The ground product is then removed from the agitator ball mill 1 a via the ground stock outlet 5 .

FIG. 2 shows a schematic view of another agitator ball mill 1 b with a horizontally arranged grinding vessel 2 and agitator 3 according to the prior art. The agitator ball mill 1b comprises an upper grinding stock inlet 4 and a grinding stock outlet 5 centrally arranged on the opposite side of the grinding vessel 2, a separation device 6 assigned to said grinding stock outlet. The separating device 6 blocks the grinding bodies M in the grinding container 2 . The agitator ball mill 1b also comprises a pre-grinding device 7 connected to the agitator shaft 3*. The pre-grinding device comprises a comminution cone 8 arranged rotatably fixed to the stirring shaft 3 * of the stirrer 3 and a comminution ring 9 fixed to the grinding container 2 . The ground material is introduced into the grinding gap S between the grinding cone 8 and the grinding ring 9 and is thus pre-ground before it enters the grinding container 2 in which it passes through the agitator 3 And grinding body M is further processed. The ground product is then removed from the agitator ball mill 1 b via the ground stock outlet 5 . The pre-grinding device 7 includes a gap protection for the grinding chamber 2R which prevents the grinding bodies M from being able to flow back and enter the pre-grinding device 7 .

The pre-grater device 7 according to the invention (see in particular FIG. 6 ) comprises a stationary first grater 20 (see FIG. 3 ) and a rotatably movable second grater 30 (see FIG. 4 ). A grinding gap S is formed between the first grater 20 and the second grater 30 . In particular, the first grater 20 is designed as a so-called grater ring 21 and the second grater 30 is designed as a so-called elongated truncated cone 31 . The pre-grinding device is arranged between the grinding material inlet 4 and the grinding chamber 2R (see also FIGS. 1 , 2 and 6 ) in such a way that the second grinding means on the side facing the grinding chamber 2R 30 engages at least partially into the first grinding device 20, thereby forming a grinding gap S through which the ground material must pass when entering the grinding chamber 2R, whereby it is pre-ground.

Fig. 3 shows several views of the first grater 20 of the pre-grater device according to the invention, in particular Fig. 3B shows a section along the section line A-A according to Fig. 3A. The first grater 20 is designed in particular as a grater ring 21 . The inner circumferential surface 24 of the grinder ring 21 comprises a so-called internal tooth system comprising internal teeth 26 .

FIG. 3C shows a perspective view of the first grater tool 20 embodied as a grater ring 21 , and FIG. 3D shows a detail of FIG. 3A . In particular, it can be clearly seen here that the internal tooth system in the inner circumferential surface 24 has fine internal teeth 26 .

Fig. 4 shows several views of the second grater 30 of the pre-grater device according to the invention, in particular Fig. 4C shows a section along the section line A-A according to Fig. 4B. Figure 4D shows details of Figure 4C. FIG. 4E shows a top view of the second grater 30 viewed on the top face DF.

The second grater 30 comprises a region in the form of a truncated cone 35 and a cylindrical region 34 . The region formed as a frustum 35 has a base GF, a top DF and an outer side surface AF ₃₅ . The cylindrical region 34 comprises a cylindrical base ZF having the same section or the same diameter as the base GF of the frustum 35 and an outer side surface AF ₃₄ .

The second grater 30 at least partially includes first external teeth 36 . Furthermore, the second grater 30 at least partially comprises second external teeth 37 . In particular, the second grater 30 comprises a first cylindrical region 34 having first teeth 36 and a second frustoconical region 35 having first teeth 36 and a second frustoconical region 35. Teeth 37, the first tooth 36 has a first material thickness and/or a first material height, the second tooth 37 has a second material thickness and/or a second material height, and wherein the first material thickness and/or the first material height Less than the second material thickness and/or the second material height. In particular, the first material thickness and/or first material height of the fine outer teeth 36 of the second grater 30 corresponds at least largely to the material thickness and/or material height of the inner teeth 26 of the grinding ring 21 (also See Figure 3).

The so-called sparse teeth 37 of the second grater 30 are formed in the entry region of the pre-grater 7 as finer and finer teeth 36 than the second grater 30 and/or the first grater 20 or the grater ring The fine and dense internal teeth 26 of 21 are thicker. The sparse second teeth 37 in the second region 35 of the second grater 30 also have a tapered tooth shape. In particular, the tooth shape is in the direction of the free end region of the second grater 30 facing away from the grating ring 21 or at the top surface DF of the second region of the second grater 30 formed as a frustum 35 tapered in direction.

According to a preferred embodiment, the finer teeth 36 extend on the outer side surface of the outer sparser teeth 37 . As a result of the more sparse second outer teeth 37 of the second grinding tool 30 , coarse particles of the grinding stock can be better picked up and pre-ground. The entire pre-grinding device is constructed and arranged between the grinding material inlet 4 and the grinding chamber 2R (see also FIGS. 2 and 6 ) in such a way that no dead space is formed as far as possible, so as to avoid coarse particles and/or impurities due to grinding The material is stuck.

According to an alternative embodiment of the invention, the sides delimiting the outer side surfaces of the sparse outer teeth 37 have a curved course. In particular, one of the two sides has a more pronounced curvature, as a result of which a widening of the external toothing 37 in the direction of the adjacent cylindrical subregion 34 is formed.

5 shows details of the tooth system between the first grater 20 and the second grater 30, in particular the fine inner teeth 26 of the grater ring 21 and the cylindrical region 34 of the second grater 30. Detail of fine outer teeth 36 . The fine-grained inner teeth 26 and the fine-grained outer teeth 36 mostly engage with each other, thereby forming a grinding gap S. As shown in FIG. The grinding gap S defines the minimum distance between the fine inner teeth 26 of the grinding ring 21 and the finer outer teeth 36 of the cylindrical region 34 of the second grinding tool 30, so that the grinding gap S into the grinding chamber 2R The grinding material (see Figure 1, Figure 2 and Figure 6) is pre-ground. The combination of the fine tooth system 26, 36 and the sparse tooth system 37, in particular with the tapered tooth shape of the sparse tooth system 37, results in an improved penetration behavior in the case of coarse-grained product components, in particular is when the milling material includes product components of different sizes. Furthermore, a deeper tooth depth is formed on the inlet side by means of a sparse tooth system 37 . A better pumping effect and/or turbulence is thus achieved by means of the pre-grinding device according to the invention, which prevents the product from sticking in the inlet region 10 (see FIGS. 2 and 6 ).

The invention has been described with reference to the preferred embodiments. However, a person skilled in the art may envisage modifications or changes to the invention without thereby departing from the scope of protection of the following claims.

List of reference signs

1 stirring ball mill

2 grinding containers

2R grinding chamber

3 stirrers

3*stirring shaft

4 Grinding material inlet

5 Grinding material outlet

6 separation device

7 pre-grinding device

8 smash cones

9 smash rings

10 entrance area

20 first grater

21 grating ring

24 inner peripheral surface

26 internal teeth

30 second grater

31 slender truncated cone

34 Cylinders/Cylinder Areas

35 area constituted as a truncated cone

36 fine outer teeth

37 sparse outer teeth

AF external side surface

d diameter

DF top surface

GF Bottom

M grinding body

Q profile

S crushing gap/grinding gap

ZF cylinder - bottom surface

Claims (12)

1. the pre-grinding device (7) that is suitable for ball mill or agitating ball mill (1), wherein said pre-grinding device (7) is arranged on the grinding material inlet (4) of described ball mill or agitating ball mill (1) and grinds between chambers (2R) and comprising a fixed first grinding device (9, 20) and a rotatably movable second grinding device (8, 30), in which the first grinding device (9 , 20) and the second grinding tool (8, 30) form a grinding gap (S), and wherein the first grinding tool (9, 20) configured to be fixed is arranged in the grinding container ( 2) Grinder ring, characterized in that the fixed first grater (20) comprises an internal tooth system, and the second grater (30) comprises a first subregion (34) and a second subregion an area (35), wherein said second sub-area (35) comprises guide structures adapted for grinding material, by means of which grinding material can be guided in the direction of said first sub-area (34), and wherein At least said first subregion (34) of said second grater (30) comprises a first external tooth system, wherein said first grater (20) and said second grater (30) arranged such that the external tooth system of the first subregion (34) of the second grater (30) engages largely with the internal tooth system of the first grater (20), thereby forming The grinding gap (S). 2. The pre-grater (7) according to claim 1, characterized in that the second grater (30) comprises a second external tooth (37) in the second sub-region (35) ) of the second external tooth system, wherein the second external tooth (37) has a second tooth height and a second tooth width, the second tooth height and the second tooth width are greater than those in the second grinding tool ( A first tooth height and a first tooth width of the first external teeth (36) in said first sub-region (34) of 30), and wherein said second external tooth system forms a guide structure suitable for grinding material. 3. The pre-grinding device (7) according to claim 2, characterized in that, the tooth width of the second external tooth (37) is from the free end of the second sub-region (35) in the adjacent The direction of the first sub-region (34) increases, and/or the tooth height of the second external teeth (37) decreases in the direction of the adjacent first sub-region (34). 4. The pre-grater (7) according to claim 2 or 3, characterized in that the sides delimiting the outer surfaces (AF ₃₅ ) of the outer teeth (37) have a curved course, in particular that of the two sides One side of has a more pronounced curvature. 5. The pre-grinding device (7) according to any one of claims 2 to 4, characterized in that, the The first external tooth system continues on the outer surface (AF ₃₅ ) of the second external tooth system of the second subregion (35) of the second grater (30). 6. The pre-grating device (7) according to any one of claims 2 to 5, characterized in that the second subregion ( 35) Constructed in the form of a frustum having a frustum base (GF) and a frustum top (DF), and wherein said first of said second grater ( 30 ) is rotatably movable The subregion (34) is formed as a substantially cylindrical region with a cylindrical base (ZF), wherein the frustum base (GF) is substantially identical to said cylindrical base (ZF), and wherein there is an approximately A cylindrical region (34) is located adjacent to the frustum base (GF) of said frustoconical region (35). 7. Pre-grater device (7) according to claim 6, characterized in that the substantially cylindrical area (34) comprises a first external toothing system with first external teeth (36), said first external teeth ( 36) Having a first tooth height and a first tooth width, said first external teeth (36) being configured to substantially correspond to said internal teeth (26) of said internal tooth system of said first grater (20) ), and wherein said first grater (2) and said second grater (30) are arranged such that: said external tooth system of said cylindrical region (34) mostly engages to said first The internal tooth system of the grater (20), thereby forming the grater gap (S). 8. The pre-grinding device (7) according to claim 6 or 7, characterized in that the second grater (30) is on the top surface (DF ) and the outer side surface (AF ₃₅ ) between the truncated cone base (GF) comprises a second external toothing system with a second external toothing (37), wherein the second external toothing (37) having a second tooth height and a second tooth width greater than the first outer teeth (36) in the cylindrical region (34) of the second grater (30) ) of the first tooth height and first tooth width. 9. The pre-grinding device (7) according to claim 8, characterized in that the tooth width of the second external teeth (37) extends from the apex of the truncated cone region (35) The face (DF) increases in the direction of said cylindrical area (34), and/or the tooth height of said second external toothing (37) decreases in the direction of said cylindrical area (34), in particular, bounding The outer surfaces (AF ₃₅ ) of the sides of the outer teeth (37) have curvature, in particular one of the sides has a more pronounced curvature. 10. The pre-grater (7) according to any one of claims 7 to 9, characterized in that the outer teeth of the cylindrical region (34) of the second grater (30) The system continues on said outer surface (AF ₃₅ ) of said second external toothing system of said frustoconical region (35) of said second grater (30). 11. A ball mill, especially an agitating ball mill (1), has a pre-grinding device (7) between the grinding material inlet (4) of the ball mill or agitating ball mill (1) and the grinding chamber (2R), wherein the pre-grinding The device (7) comprises a fixed first grinding device (9, 20) and a rotationally movable second grinding device (8, 30), between said first grinding device (9, 20) and A grinding gap (S) is formed between the second grinding devices (8, 30), and wherein the first grinding device (9, 20) configured as fixed is a grinding device arranged in a grinding container (2). ring, characterized in that the fixed first grater (20) comprises an internal tooth system, and the second grater (30) comprises a first subregion (34) and a second subregion (35), wherein The second sub-area (35) comprises a guide structure suitable for grinding material, through which the grinding material can be guided in the direction of the first sub-area (34), and wherein at least the second grinding The first sub-region (34) of the grater (30) comprises a first external tooth system, wherein the first grater (20) and the second grater (30) are arranged such that: the The external tooth system of the first sub-region (34) of the second grater (30) is largely engaged to the internal tooth system of the first grater (20), thereby forming the grater gap ( S). 12. The ball mill according to claim 11, in particular the stirring ball mill (1), characterized in that it comprises a pre-grinding device (7) according to any one of claims 2 to 10.